1. Technical Field
The present invention relates to a device for preventing the intensity reduction of an optical signal, an optical emission spectrometer, an optical instrument, and a mass spectrometer including the same.
2. Background Art
In general, in a processing of wafers and the like of semiconductor elements, a plasma process is widely used and particularly, in the processing of DRAM wafers and the like which are expansively used due to universalization of PCs and the like, it is required that wafers having a size of 30 cm are produced at a high yield by the plasma process.
For the processing uniformity of the wafers, it is required that a necessary etching process is exactly progressed by exactly and stably controlling a plasma source and it is more important to exactly control a plasma field generated from the plasma source according to the refinement of wafer patterns.
Accordingly, in order to measure the plasma process used in a semiconductor manufacturing process, various contact measuring techniques such as various optical techniques such as a laser fluorescence spectrometric method, an emission spectrometric method, an absorption spectrometric method, etc., an electric probe, a mass spectrometer, an inductive coupled plasma (ICP), and the like.
However, when the plasma is measured by the optical techniques using the optical emission spectrometer and the like, a measured intensity of the optical signal is reduced due to contamination of a receiving optical window and as a result, the receiving sensitivity of a measuring instrument is lowered, such that it is impossible to measure the plasma in many cases.
Further, even in a device of analyzing components by absorbing gases such as the mass spectrometer, the ICP (inductively coupled plasma), and the optical emission spectrometer, since reactive ions and particles are absorbed to a detector in the absorbing process of the gas, the performance of the detector is deteriorated.
Further, since RF electromagnetic waves, ultrahigh frequencies, and the like are radiated in a plasma generation process or the generated plasma, if the insides of the optical emission spectrometer and the mass spectrometer are exposed by the harmful electromagnetic waves as it is, malfunction of communication equipment may occur, such that in order to solve the problems due to the harmful electromagnetic waves, measures are required.